Small-signal response of a semiconductor laser with inhomogeneous linewidth enhancement factor: Possibilities of a flat carrier-induced FM response

Abstract

It is shown that inhomogeneities in the linewidth enhancement factor in a semiconductor laser exert great influence on the injection current modulation FM response. Several phenomena, which have not been explained so far, such as redshift frequency chirping, flat carrier induced FM response, and absence of phase reversal at the thermal cut-off frequency, are explained by the present theoretical model. A flat carrier induced FM response with either redshift or blueshift may be obtained in a semiconductor laser with an inhomogeneous linewidth enhancement factor without the accompanying spurious intensity modulation.